High nest predation rate in the Chaffinch

Abstrakti

The breeding biology of an individually marked Chaffinch Fringilla coelebs population was studied in coniferous forest in Lammi, in southern Finland, in 1990-91 . In addition, the nesting success was analysed in the Finnish nest-card data from the years 1986-1991. Nest predation, calculated from the nests found during the building stage, was high both in Lammi (87 .5%) and in the nest-card data (70.1 %) . Nest height or nesttree species in the nest-card data had no effect on nest survival . Nest predation seems to be a major factor affecting breeding success and probably lifetime reproductive success in the Chaffinch. It seems that the nest predation in this species is a probabilistic process which the parent birds are hardly able to influence. We discuss the implications ofthe high nest predation rate for the breeding behaviour of the Chaffinch.